Analysis of populations of excited states of ions and its application to electron temperature and density measurements

In the present work the stepwise excitation of ions is discussed and the electron density Ne at which the solar corona model is applicable to a plasma is estimated. For this case the populations of the 21D2 and 33P20 states of CIII ion are calculated. Expressions for the ion density for selected excited states for which the corona relations are not applicable are obtained taking into account collisional de-excitation. The dependence of the density of CIII ions in the states 21D2 and 33P20 upon Ne and kTe is determined for this particular case. The results of these theoretical considerations are illustrated by electron temperatures and densities determined by an analysis of the excited states of CIII ion for a rod plasma gun.